Process of making pure ammonium chlorid.



UNITED STATES PATE o EIcE.

rnaNcrs ARTHUR FBEETH, or GREAT CROSBY, AND HERBER'rnDWIN COCKSEDGE, or

' HERNE HILL, LONDON, ENGLAND.

PROCESS OF MAKING PURE AMMONIUM CHLORID.

No Drawing.

I To'all whom it may concern:

Be it known that we, FRANCIS ARTH R 'Fnmrrn and HERBERT EDWIN Coonsnocn,

subjects of the King of Great Britain, residing, respectively,.at Great Crosby, 1n the county of Lancaster, and Herne 11111, S. E., London, both in the Kingdom of England,

have invented certain new and useful Processes for Making Pure. Ammonium Chlorid, of which the following is a Specification.

In our Patent No. 970,909, we described a process for the preparation of pure or practically pure ammonium chlorid directly and 'without recrystallization by the reaction between equivalent quantities of sodium chlorid and ammonium sulfate at atemperature of 103 C. or thereabout, when the reaction is performed in the presence of that quantity of water which will sufiice to yield after the completion of the reaction, a solution saturated with respect to ammonium chlorid and sodium sulfate at the temperature of the reaction.

.We have now discovered a process which enables us'to prepare at temperatures below 100 C. pure or practically pure ammonium chlorid directly and without recrystallization by the reaction between equivalent quantities of ammonium sulfate and sodium chlorid in presence of a solution containing ammonium chlorid, sodium orocess the ammonium chlorid obtained by cooling, the products in solution resulting; from the reaction between the equivalent quantities of ammonium sulfate and sodium chlorid added to the nucleus' solution) is to be removed from the solut1on,- anhytrons sodium sulfate is added until no inorefavil l d solve, and then a} quantity of sodium chlorid the ratio (if which to the water present in the nucleus solution depends upon the temperature at which the anhydrous. precipitated sodium sulfate (formed by the reaction between the equivalent quantities of ammonium sulfate and sodium chlorid subsequently added to the nucleus solution) is to be removed from the solution. Hydrated sodium sulfate may be employed in the preparation of the nucleus solution instead of the anhydrous,

salt provided that the quantity of water used be reduced by an amount equivalent to that contained in thehydratedsalt. The quantities of ammonium sulfate and sodium chlorid added to this nucleus solution, always in equivalent proportions, -aresuch that the resultant solutionafter completion of the reaction is saturated or'nearly saturated with regard to ammonium chlorid at the temperature of the reaction and is'of course also saturated with re ard to sodium sulfate, inasmuch as this salt is precipitated. This nucleus solution is only prepared once. At the endof the processuhich results in the separation of solid ammonium chlorid, the nucleus, solution reproduces itself automatically, that is, the solution remaining after the separation of ammonium chlorid is identical in con'iposition with the original nucleus solution. It is subjected to a fresh cycle of operations by addition of equivalent uantities of ammonium sulfate and sodium chlorid to the same amount as before, when sodium sulfate and ammonium chlorid are again formed, and so on. The number of cycles may be repeated indefinitely.

When the reaction bet-ween the equivalent quantities of ammonium sulfate and sodium chlorid added to the nucleus solution is complete, that is,,when the .whole of the ammonium sulfate has been transformed into anuuoniun'i chlorid, the anhydrous sodium sulfate precipitated is removed at the temperature at which the reaction is performed, and the liquor remaining is cooled to sepa- Speciflcation of Letters Patent. Patented Aug, 13, 1912. Application filed December 10, 1910. Serial No. 596,34.

rate ammonium chlorid. The sodium sulfate, after washing to remove adherent mother lit nor, is pure or'pr'actically pure. Now we have discovered that this l quor from which the precipitated sodium sulfate 'has been removed must not be cooled below temperature it is free from sodium sulfate. This minimum temperature depends upon the temperature at which the reaction between the equivalent quantities .of ammonium sulfate and sodium chlorid is performed. The higher the reaction temperature, the higher also is this minimum temperature. This minimum temperature below which the liquor must not be' cooled is definite and fixed for each temperature at which the rel dium chlorid, in 100 parts of water. The,

action is performed.-

' Our-process therefore consists in first prearin ,the nucleus. solution as above describe and then adding to it, either before, durin or after heating to the temperature at which the reaction between ammonium sulfate and sodium chlorid is 'to be performed, (such temperature being always below 100 equivalent quantities of ammonium s after the reaction between them is complete,

that is, after the whole of theammonium sulfate has been transformed into ammonium chlorid, the resultant solution is saturated or nearly saturated as regards ammonium chlorid at the temperature of the reaction. 1

The mixture, during, and after, the addition of ammonium sulfate and sodium chlorid is stirred and meanwhile maintained at the temperature selected for the reaction until the whole of the ammonium sulfate has been transformed into ammonium chlorid. Any loss of water which occurs during this operation by evaporation must be compensated for by the addition of an equivalent quantity of water, either as.

such, as wash liquor from a previous operation, or in the form of brme-tha t 1s, a solution of common salt in water: the latter case the quantity of solid sodium ChlOIld performed. A

" The ammonlum chlorid preci itated is separated from the solution, was ed to remove adherent mother li uor, and then dried or drained by any well own means: it'is then free or practically free from sodium sulfate 'or other impurities. The liquor which remains after the separationof ammonium chlorid is identical in' composition with the ori 'nal nucleus solution. Equivalent quantities of ammonium sulfate and sodium chlorid are again added exactly in the same wayas, and in the same quantities ate and sodium chlorid, either together or separately, in such amount that hour or more.

as before; the process is then repeated as before at exactly the same temperature, and so on indefinitely. I

The following are examples of the method by which the process can be carried out Example I When the temperature se.- lected for the reaction is 85 0., a nucleus liquor 1s prepared-by dissolving 33.3 parts of ammonium chlorid, 26.2 parts of anhydrous sodium sulfate, and 4.5 parts of sosolution is agitated and, either while it is being heated to 0., or when it is at that temperature, 37.9 parts of ammonium sul-" fate-and 33.6 parts of sodium chlorid are added, either together or separately, these being equlvalent quantities of the twosalts, and the total quantity that which will, after completion of the reaction, give a solution ]ust saturated with respect to ammonium chlorid at 85 0. The agitation is con-' tinued and the whole maintained at 85 0.,

anyloss of water by evaporation being made up as previously explained, until the am- '7 monium sulfate is completely transformed into ammonium chlorid: this may require an v The anhydrous sodium sulfate precipitated is then separated at 85 0. and the liquor is cooled to a minimum temperature of 25 0. this being the temperature to which it can be cooled in this case without separation of sodium sulfate together with ammonium chlorid. The

ammonium chlorid is removed at the same temperature by any well known means, and

after washing is pure, or practically pure- The liquor remaining after the separation of the ammonium chlorid hasthe same composition as the original nucleus solution, and

is ready for treatment with equivalent quantities of ammonium sulfate and sodium chlorid as aaove: this cycle can be repeated indefinitely.

Example II: \Vhen'the temperature selec'td for the reaction is 60 0., a nucleus solution is-prepared by dissolving 27.3 parts of ammonium chlorid, 20.0 parts of anhydrous sodium sulfate, and 10.2 parts of sodium chlorid, in arts of water. To this solution, either w on being heated. to 60 0., or when at that temperature, is added 22.7 parts of ammonium sulfate and loo 20.1 parts of sodium chlorid, these being.

equivalent quantities, and the total quantity such as will suffice to just give a solution saturated with respect to ammonium chlorid at 60 0. when the reaction is complete. The reaction is completed under the same conditions and with the same precautions as be fore, but at 60 0. 'The anhydrous sodium cooled without separation of sodium sulfate suifate precipitated-is removed at 60 0. and

with the ammonium chlorid. The ammo-' nium chlorid precipitated on cooling is then separated as previously described, and the so utionremaming has the same composition as the nucleus solution originally used, and isready for afresh cycle'of operations as above.

. 1 We declare-that what ,we claim is 1. The herein-described improved process for making pure ammonium chlorid from ammonium sulfate and sodium chlorid .Which consists in stirring together at temperatures below' 100 C. equivalent quantities ;of ammoniumsulfate and sodium chlorid-with that quantity of the herein described nucleus solution containing ammo-- lostby evaporation: then separating out at that same temperature the precipitated anhydrous sodium sulfate and washing it:

' coolin the liquor remaining after separation.

sulfate is precipitated from it: removing the ammonium chloridwhich separates ut and washing it to remove adhering-nucl f s solu- 2. {lhe process of making pure ammonium OlllOlld,. which consists in causing to react at a temperature of substantially 85 ,centigrade substantially equivalent' quantities of ammonium sulfate and sodium chlorid, namely, substantially 57.9 partsof 'fammoenium sulfate 'and'33.6 parts of sodium chlo-.

rid, in the presence of 100 parts of a nucleus solution, the composition of which-solution consists of substantially 33.3 parts'of ammonium chlorid, 26.2 parts of anhydrous so-.

dium sulfate, and 4.5 parts of sodium chlorid in 100 parts of water; agitating the mixture at or about the temperature selected for.

the reaction until all the ammonium'sulfate f is converted into ammonium chlorid; add-- ing water in sufiicient'quantity to compensate for any evaporation; removing the precipitate of anhydrous sodium sulfate at the temperature of I it; cooling the solution fromlwh ich the so dium sulfate precipitate has been removed; separating the precipitated ammonium chlo rid; and washm'g'it, whereb thesoluti'on remaining after separating t e ammonium chlorid constitutest chosen in the previous reaction,

In witness whereof, we have hereunto signed our names this 28 day otNovember 1910, in the presence of tivosubscribing 'v'vitnesses. tion o '-the precipitated sodiumsulfate to a -temperature above that at which sodium rmcis Animis tantra. I HERBERT EDWIN UOGKSEDGE. Witnesssa. I H

-W1u. I. THOMPSO GHAs, Leanna,

ie nucleus solution afore-' said for the reaction at, the temperature the: reaction and washing 

